Wasn't there some regulation regarding privacy coins about a year ago being discussed? I remember something vaguely. Most likely I think Bittrex is taking caution because of how SEC cracked down on XRP. Or they got some private memo and we might see these privacy coins being delisted on other exchanges.

This pretty much happens whenever crypto is at ATH and regulations always take place shortly after. Basically crypto being thrown under the radar and first it was self-hosted wallets needing KYC, then ripple being sued, now privacy coins are targetted and next thing we know they will go after ETH because it had a premine. Crazy times.